Objective  To investigate clinical characteristics and risk factors of different stages of urinary tract infection after kidney transplantation.

  Methods  Clinical data of 209 kidney transplant recipients were retrospectively analyzed. According to time points of postoperative follow-up, all recipients were divided into 3 stages: within 1 month post-kidney transplantation, 1-6 months post-kidney transplantation, and 7-12 months post-kidney transplantation. The incidence of urinary tract infection, urine culture results of recipients with urinary tract infection and drug resistance characteristics of common pathogens during different stages after kidney transplantation were analyzed. The strains of patients with recurrent urinary tract infection were identified. The risk factors of urinary tract infection and the effect of urinary tract infection on renal allograft function were analyzed.

  Results  The urinary tract infection rate was 90.0% in the first stage, 49.3% in the second stage and 22.5% in the third stage. The urinary tract infection rates of male recipients undergoing living-related organ donation in the second and third stages were lower than those of female recipients (both P<0.05). Urine culture test yielded positive results in 60 cases, and 84 strains of pathogenic bacteria were detected, mainly Gram-negative bacteria, among which Klebsiella pneumoniae accounted for the highest proportion. Sixty-six recipients had recurrent urinary tract infection, and the detected pathogens included Klebsiella pneumoniae, Escherichia coli and Candida glabrata, etc. Univariate analysis showed that postoperative use of antithymocyte globulin was the risk factor for urinary tract infection in the first stage. Preoperative urinary tract infection and donor type were the risk factors for urinary tract infection in the second stage. Gender and age of the recipients were the risk factors for urinary tract infection in the third stage. Multivariate analysis revealed that postoperative use of antithymocyte globulin was the risk factor for urinary tract infection in the first stage. Gender and age of the recipients were the risk factors for urinary tract infection in the third stage (all P<0.05). In the third stage, 65 cases were cured and 38 cases were not cured. In the treated recipients, the serum creatinine level and white blood cell count were decreased after corresponding treatment than those before treatment (both P<0.05).

  Conclusions  Gram-negative bacteria are the main pathogens of urinary tract infection in kidney transplant recipients, and drug resistance is relatively high. Postoperative use of antithymocyte globulin, female and old age are the risk factors for urinary tract infection in kidney transplant recipients.